1. Field
The described technology relates generally to a unit mask supported by a frame and a mask assembly.
2. Description of the Related Technology
Examples of a flat panel display include an organic light emitting diode (OLED) display, a liquid crystal display (LCD) and a plasma display panel (PDP).
To manufacture the OLED display, it is typically necessary to form an electrode in a specific pattern, and an emission layer. A deposition method using a mask assembly can be used to form the electrode and the emission layer.
A conventional mask assembly generally includes a frame having an opening and a plurality of unit masks in a band shape. Both ends of each unit mask are extended corresponding to the opening and fixed to the frame. The unit masks can include patterned openings corresponding to pixels of OLED displays such that the OLED displays can be manufactured on a mother substrate. The patterned opening of each unit mask can correspond to a single OLED display and is formed in a shape corresponding to an electrode or an emission layer to be formed in the OLED display.
When a high definition OLED display is required, a fine patterned opening is formed in the unit mask. To achieve this, the unit mask needs to be very thin (in μm) in order to prevent unintended deposition error because of characteristics of a deposition process.
However, when the unit mask becomes very thin, it can be difficult to weld both ends of the unit mask to the frame to fix the unit mask to the frame.
Furthermore, when the unit mask is very thin, the unit mask may sag through the opening since both ends thereof are extended and fixed to the frame or the unit mask may deformed due to a tensile force applied to the unit mask.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the described technology and therefore it may contain information that does not form a part of the prior art that is already known in this country to a person of ordinary skill in the art.